Calling a C function from Fortran where the C function name was originally passed in from C

Question

For reasons that are not relevant, I need to pass a C/C++ function name into a Fortran subroutine, which, in turn, calls that C function. What I have found is that I can succesf

Answer 1

I would change the interface definition to read

interface
    subroutine calledfromFortran(status) bind (c)
        use iso_c_binding
        integer(kind = c_int), VALUE :: status
    end subroutine calledfromFortran
end interface

I am not sure what intent(in) was, but that bit of the code does not look right. Apart for that, the rest looks (at first pass) reasonable and right.

Note. The ISO C bindings were only added in the 2003 releae of the FORTRAN language, so if you are using an older version it might be worth checking the compiler documentation for details. Some compilers allow ISO C bindings, but maybe called slightly differently than that I have displayed above.

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Edit. Having looked into the intent keyword, you might try using intent(in) in conjunction with the following type declaration, that follows the interface definition

integer (c_int), parameter :: one = 2

I hope this helps.